Modeling Alkali-Silica Reaction Using Image Analysis and Finite Element Analysis

2011 ◽  
Vol 250-253 ◽  
pp. 1050-1053
Author(s):  
Jun Ho Shin ◽  
Nam Yong Jee ◽  
Leslie J. Struble ◽  
R. James Kirkpatrick

The objective of this study is to develop a numerical model based on microstructural images of concrete and fundamental material properties of each constituent of concrete subjected to alkali-silica reaction (ASR). A microstructure-based finite element approach is employed directly to analyze the mechanical response of concrete to ASR. The modeling work involves acquiring and processing of microstructural images of specimens suffering from ASR using scanning electron microscopy, and implementing finite element program to analyze the microstructural images. The formulation of this model is based on pressure caused by the ASR product and on properties such as Young’s modulus and Poisson’s ratio. The finite element analysis program used to simulate structural behavior of structures attacked by ASR is object-oriented finite element developed at National Institute of Standards and Technology. The numerical results from this model are compared with experimental data, which have been measured using ASTM standard test C1260. The results show that the development and widening of cracks by formation and swelling of ASR gel cause the majority of expansion of mortar specimens rather than elastic elongation due to gel swelling.

Author(s):  
Makoto Tanabe ◽  
Hajime Wakui ◽  
Nobuyuki Matsumoto

Abstract A finite element formulation to solve the dynamic behavior of high-speed Shinkansen cars, rail, and bridge is given. A mechanical model to express the interaction between wheel and rail is described, in which the impact of the rail on the flange of wheel is also considered. The bridge is modeled by using various finite elements such as shell, beam, solid, spring, and mass. The equations of motions of bridge and Shinkansen cars are solved under the constitutive and constraint equations to express the interaction between rail and wheel. Numerical method based on a modal transformation to get the dynamic response effectively is discussed. A finite element program for the dynamic response analysis of Shinkansen cars, rail, and bridge at the high-speed running has been developed. Numerical examples are also demonstrated.


1991 ◽  
Vol 226 ◽  
Author(s):  
Yi-Hsin Pao ◽  
Kuan-Luen Chen ◽  
An-Yu Kuo

AbstractA nonlinear and time dependent finite element analysis was performed on two surface mounted electronic devices subjected to thermal cycling. Constitutive equations accounting for both plasticity and creep for 37Pb/63Sn and 90Pb/10Sn solders were assumed and implemented in a finite element program ABAQUS with the aid of a user subroutine. The FE results of 37Pb/63Sn solder joints were in reasonably good agreement with the experimental data by Hall [19]. In the case of 9OPb/1OSn solder in a multilayered transistor stack, the FE results showed the existence of strong peel stress near the free edge of the joint, in addition to the anticipated shear stress. The effect of such peel stress on the crack initiation and growth as a result of thermal cycling was discussed, together with the singular behavior of both shear and peel stresses near the free edge.


2017 ◽  
Vol 24 (3) ◽  
pp. 415-422 ◽  
Author(s):  
Ke Chun Shen ◽  
Guang Pan ◽  
JiangFeng Lu

AbstractThe buckling and layer failure characteristics of composite laminated cylinders subjected to hydrostatic pressure were investigated through finite element analysis for underwater vehicle application. The Tsai-Wu failure criteria were used as the failure criteria for the buckling analysis. A sensitivity analysis was conducted to research the influence of the number of elements on the critical buckling pressure. ANSYS, a finite element program, successfully predicted the buckling pressure with 5.3–27.8% (linear) and 0.3–22.5% (nonlinear) deviation from experimental results. The analysis results showed that the cylinders can carry more pressure after a slight decrease in pressure and recovery of the supporting load. For layer failure analysis, it was found that the failure that occurred in the 0° layer was more serious than that in the 90° layer within the neighboring layers at the inner layers (nos. 1–7) and outer layers (nos. 8–24).


2012 ◽  
Vol 594-597 ◽  
pp. 2723-2726
Author(s):  
Wen Shan Lin

In the present study, the constitutive law of the deformation theory of plasticity has been derived. And that develop the two-dimensional and three-dimensional finite element program. The results of finite element and analytic of plasticity are compared to verify the derived the constitutive law of the deformation theory and the FEM program. At plastic stage, the constitutive laws of the deformation theory can be expressed as the linear elastic constitutive laws. But, it must be modified by iteration of the secant modulus and the effective Poisson’s ratio. Make it easier to develop finite element program. Finite element solution and analytic solution of plasticity theory comparison show the answers are the same. It shows the derivation of the constitutive law of the deformation theory of plasticity and finite element analysis program is the accuracy.


Fibers ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 52 ◽  
Author(s):  
Amgad Elbehiry ◽  
Marwan Mostafa

One of the challenges of the century is to reach compatibility between the required resistance and the usage of lightweight building materials that may negatively affect the mechanical properties. Natural fibers nowadays are used as enhancers in the industrial field. Hence, the fibers contribute by giving an ideal solution to improve mechanical proprieties of the structural elements such as tensile and impact strength. In previous studies, the use of natural fibers as reinforcement in construction materials has increased. Natural fibers have a lot of characteristics such as being strong, lightweight, inexpensive, and eco-friendly. This paper aims to investigate the performance of banana fiber bars (BFB) as reinforced material. Through this study, the development and characterization of natural fibers-based composite beams were observed. After the beams were designed, several types of finite element analysis were conducted using ‘ANSYS’ nonlinear finite element program under one-point loading. Results show good correlations between experimental and predicted results.


Author(s):  
K W Dalgarno ◽  
A J Day ◽  
T H C Childs

This paper describes a finite element analysis of a synchronous belt tooth under operational loads and conditions with the objective of obtaining a greater understanding of belt failure by tooth root cracking through an examination of the strains within the facing fabric in the belt. The analysis used the ABAQUS finite element program, and was based on a two-dimensional finite element model incorporating a hyperelastic material model for the elastomer compound. Contact between the belt tooth face and the pulley groove was modelled using surface interface elements which allowed only compression and shear forces at the contact surfaces. It is concluded that the critical strains in the facing fabric of the belt, and therefore the belt life, are largely determined by the tangential loading condition on the belt teeth.


2013 ◽  
Vol 368-370 ◽  
pp. 1583-1590
Author(s):  
Chang Ming Hu ◽  
Yan Guo ◽  
Jie Wang ◽  
Qiong Wu

An underground club in Xian is taken as the research object to explore the mechanical response of the internal poles of its high formwork support system during concrete pouring. The internal force static measurement of the high formwork support system is carried out. Each stage of the concrete pouring is simulated by the finite element analysis software ANSYS in the form of load step, whose results are contrasted with the measured results. The contrast reveals that the concrete pouring sequence has direct influence on the tendency of poles axial force and on the location of maximum axial force and that it is reasonable to adopt imaginary horizontal force which simulates the initial defects to carry out the overall stability analysis of the high formwork support system. It is pointed out that the program of setting up the formwork and the concrete pouring sequence should be determined with the finite element analysis.


Author(s):  
S W Wen ◽  
P Hartley ◽  
I Pillinger ◽  
C E N Sturgess

This paper presents a study of the mechanics of deformation of the four-roll pass cold rolling using an elastic-plastic finite element program. This process has been developed at the Anshan Institute of Iron and Steel Technology, People's Republic of China, where a new four-roll pass small section cold rolling mill has been built. The initial finite element analysis has been carried out for the rolling of 8 mm square section bar from 10 mm diameter round stock under dry friction conditions. The results show clearly how the areas of plastic deformation develop during the rolling process. The distributions of the generalized stress and the generalized plastic strain, both on the longitudinal symmetrical plane and on the transverse cross-sections of the workpiece, have been obtained, and the pressure distribution along the arc of contact has been determined. In addition, the roll separation force and the pass elongation of the workpiece predicted by the finite element program have been compared with the corresponding values measured in experiments when rolling 6.5 mm square section bar from 8 mm round material with machine oil lubrication. Good agreement has been obtained.


2000 ◽  
Vol 28 (2) ◽  
pp. 163-173 ◽  
Author(s):  
V. Sajeev ◽  
L. Vijayaraghavan ◽  
U. R. K. Rao

The finite element analysis gives the stresses and deflections of the broach and workpiece while cutting and burnishing. This has been achieved by developing a suitable finite element program for solving linear and non-linear material behaviour problems. The broach has been considered to behave elastically. In case of burnishing, the stresses on the workpiece result in yielding, and hence, non-linear material behaviour is considered for the workpiece. The program has been further modified to compute residual stresses on the broached component. The movement of a single burnishing tooth through the workpiece is simulated in a step-by-step manner, leading to residual stresses on the broached surface. The burnishing tooth and corresponding portion of the workpiece are modelled using FEM. The effect of tool-work interference and the ratio of radial to axial force on the stresses and deflections while burnishing have been studied. The residual stresses left behind on the broached component have been analytically evaluated.


Author(s):  
Andrzej T. Strzelczyk ◽  
San S. Ho

ASME Code stress assessment of pressure vessels in the power generation industry is usually done by finite element analysis using one of the two approaches. In the first, “shell-element” approach, vessels are modeled out of shell elements; primary plus bending and primary plus secondary stresses are taken directly from the finite element analysis results and the alternating stresses are based on primary plus secondary stresses prorated by respective stress concentration factors. The strength of the “shell-element” approach is its simplicity; its weakness is problematic modeling of the stress concentration and some modeling difficulties (varying wall thickness, nozzle/vessel connectivity, pressure applied to the mid-surface instead of to the inner surface.) In the second, “solid-element” approach, vessels are modeled out of solid elements; “linearized” stresses can not be taken directly from the finite element analysis results, first they must be linearized, and only then, can be compared against their allowable counterparts; the alternating stresses can be based directly on the outer/inner-surface-node-stresses, provided that the mesh of the model is fine enough to account for the stress concentration effect. The strength of the “solid-element” approach is its high accuracy; its weakness is the time consuming, sometimes ambiguous, stress linearization process. This paper proposes a modification of the “solid-element” approach, in which the time consuming linearization process is replaced by a modification of the original model. To do so, a vessel must be modeled out of quadratic 20 node solid elements; the mesh density of the model (on its surface and through thickness) must be adequate for stress concentration representation and the mesh lines in the thickness direction must be more or less normal to the surfaces. The results from this original model can be taken directly for fatigue evaluation. To obtain the “linearized” stresses the original model must be slightly modified, specifically the number of elements through thickness must be reduced to one, and the reduced integration technique is recommended. For such a modified model, the nodal stresses are equivalent to the “linearized stresses” of the original model. The equivalence is discussed on a model of a circular nozzle attached to a cylindrical vessel. The vessel loads are pressure and thermal expansion.


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